All different play styles should encouraged
As a general principle, I'm not at all sure I agree with this. Even if we limit it to "play styles which are not aimed at ruining everyone else's fun."
Many different play styles should be
permitted. However, I really do think that there are play styles that are totally legitimate, and should not be prevented in any way, but should still not be
encouraged because they will tend to operate to the detriment of the game as a whole
if they are played by a significant proportion of the playerbase.
If even 50% of our characters are in the mold of the stereotypical "Game of Thrones" power-seeker, we'll end up with utter chaos. However, having a small percentage—not sure what level would be good, maybe 5-15%, but that's just guessing—significantly
increases the fun in the game, because they will tend to create power struggles and other interesting storylines.
Similarly, with religion, it's all very well to say that we should encourage people to pick the playstyle that best suits their character, but I would say that it is of net benefit to the game to have a larger proportion than we currently do who see religion as an important force in their lives and an authority to be respected and listened to. That, of course, requires that fewer characters see religion as just something to pay lip service to while they
really serve their realms.